Metal oxide particles have possibilities that they can impart functions to optical materials, materials for electronic components, and others, and attract attension in the field of various functional materials. However, metal oxides alone, have insufficient dispersibility in organic media, and often result in agglomeration, leading to problems such as a decrease in transparency and mechanical strength. As an example in which these problems have been addressed, Patent Document 1 describes a method for producing a dispersion liquid of inorganic particulates by separately providing zirconium oxide nanoparticles, a dispersing agent (for example, phosphate ester surfactant), a dispersion medium, and finally a silane coupling agent, in order to manufacture a cured material for optical members that has a high degree of transparency and is also heat-stable and superior in resistance to yellowing. In addition, Patent Document 2 describes a method for producing a dispersion liquid of an inorganic oxide having a phosphate ester surfactant added thereto, using an inorganic oxide of which the surface has been modified with a particular silane coupling agent, in order to manufacture a resin composite that is superior in moldability, exhibits transparency, and has a high refractive index.